Retarding device for machinery



I March 28, 1933'.

s. E. T. EWING ET AL RETARDING DEVICE FOR MACHINERY Filed Aug. 17, 1951Patented Mar. 28, 1933 UNITED STATES PATENT OFFICE SYDNEY EDWARD THAGKEREWING AND ARTHUR LINDSEY EGAN, OF J'OHANNESBURG, TRANSVAAL, UNION OFSOUTH AFRICA RETARDING DEVICE FORIIAGHINERY Application filed August17,1931, SerialNo. 557,686, and in the Union of SouthAfrica August18,1930.

The present invention relates to braking, retarding, or controllingdevices for machinery, especially machinery comprising a rotating shaft.A particular application of the invention is to mine hoists which aresteam driven or otherwise ill-adapted to regenerate the energy given upby the retardation of the load, more particularly the potential energyof a descending load.

effect is produced by relatively reciprocating a piston in a cylindercontaining a liquid and having a restricted passage for the movement ofliquid from side to side of the piston.

Means are provided for varying the effective area of the passage, eithermanually, or automatically so that the resistance varies in some desiredmanner, for instance according to speed, or particularly in the case ofa hoist,

according to the conditions of hoisting.

The invention is shown in the accompanying drawing as applied to a steamwinding engine, p

Fig. I being a schematic perspective view showing the hoist machinery;

Fig. II a longitudinal section through one of the retarding cylinders;

Fig. III a perspective view of the retardin piston, and

ig. IV an end view of the same piston in another state of adjustment;

Fig. Vshows, to a reduced scale, 2. development of the periphery of thepiston shown in Fig. IV. p I In Fig. I, 2 indicates the winding drumscarried on a shaft 3. 4 indicates one of the steam cylinders of thewinding engine and 5 the piston rod thereof connected to the shaft crank6 by the connecting rod 7.

Alined with each engine cylinder is the brake cylinder 8 containing apiston 9. The tail rod 10 of the steam piston may extend into the brakecylinder 8 and is connected to the piston 9, as at 11. The piston 9 ispro vided with a tail rod consisting of the shaft 12 and the fillingsleeve 13' which is of the same diameter as the rod 10 in order tobalance the piston 9; stuffing boxes 14 being provided for said rods.

The brake cylinder is fitted with a jacket 15 According to thisinvention the braking having an inlet 16 and an outlet 17 for thecirculation of Water by which. the energy taken from the hoist issystematically disposed of. i

The brake piston 9 is provide through itself the variable passage bywhich the liquid passes from one-side to the other of it when it isreciprocated. For this purpose it is composed of a number of sections18, 19, 20, 21, 22, formed with sectorshaped'wings numbered 23, 24, 25,and relativelyrotatable so that the wings can be opened or closed.fanwise; the segmental spaces 26 left between the wings constitutingthe passage for liquid. The more relatively 6 movable sets of wingsthere are provided, the less is the projected area they will-occupy whenclosed up and therefore the greater is the maximum opening of thepassage. The piston shown is provided with three relative- 7 ly movablesets of wings, enabling the angular extent of the passage to bevaried.between 0 degrees and 240 degrees.

The piston accordingly comprises three relatively rotatable units allmounted on 7 the shaft 12. Oneunit comprises the end piston sections 18and 22 which are made nonrotatable as by means of tongues 27 fittinginto grooves 28 in the cylinder wall. This unit provides the wings 23each of approxi-B mately 30 angular extent and spaced apart. The secondunit'consists of the sections 20 and 21 which are made separate topermit assembly of the piston but .which when in place are both securedto the shaft 8 12 by a key 29 so as to be rotated thereby; This unitcomprises the four wings 25 similar to the wings of the firstunit andarranged to be in alinement with the latter, as shown in Fig. III in onelimiting position of the piston units. n

The'third unit consists of the sections 19 providinga set of wings 24which is similar to the'sets 23and 25 and can aline with said sets asshown in Fig. II. This unit is loose 9 on the shaft 12 but isllimited toan angular movement of 30 fromthe Figl'III position by a pair of stops30 on the section 18, one of i which appears inFig. III. A similar pairof stops 31 on the unit 19 enables said unit 1 so constructed as to tobe rotated from the Fig. III position by the unit 20, 21 but with a lostmotion of 30. Unit 20, 21 can therefore make a maximum movement of60,during which it moves unit 19 through 30. Accordingly by suitablyrotating the shaft 12, all the sets of wings may be alined as shown inFig. III when'the liquid passage 26 through the piston will be themaximum, or they may be angularly spread out as shown in Figs. IV and Vfrom which it will be seen that the four wings 23 form fixed abutmentsat the ends of the piston and that the two sets of four wings 24' and-25move into position to form a series of steps extending between eachconsecutive pair of Wings 23 and completely closing the passage throughthe piston. It will be evident that the wings 24 and 25 may be arrangedat any positions intermediate between the positions of Fig. III andFigs. IV and V respectively. With the wide angular opening attainable inthe first position, the resistance oifered by the liquid to thereciprocation of the piston 9 in the cylinder 8 can be so small as to benegligible for the purpose in view. The resistance increases with thedecrease of the opening26 and may be made as greatas is desired bysuitably arranging the minimum opening.

32 indicates ball bearings which are interposed between the relativelyrotatable parts in order to facilitate the rotation of the shaft 12notwithstanding the heavy axial pressures towhich the piston sectionsmay be exposed when'the brake is in operation.

For effecting the angular adjustment of the shaft12 the latter is fittedexternally of the cylinder 8 with a head 33 having a feather 341'engaginga slot 35 and a sleeve 36. The latter is rotatable but otherwisefixed and is provided with a crank arm 37 for rotating it.

In the example shown the rotation of the sleeve is effected by cams 38such that resistance is automatically applied to the hoist according tothe conditions under which the hoist is operating. For example there maybe two pairs of cams, one pair for use when the load on the hoist is adescending load, the other pair for use when the load is an ascendingone; the individuals of the pairs being used according to the directionof rotation of the hoist. Said cams are connected to the drums 2 bygearing 39 so that they always rotate therewith and the proper cam isbrought into operation by sliding an arm 40 on the shaft 41 to engagesuch cam. The cam moves the arm 40 and shaft 41 angularly and said shaftis connected by gearing 42 to the sleeve 36 so as to rotate the latteras determined by the profile of the, cams.

.In the case for example where. men or stores. are being lowered intothe mine, the relevant cam' would be such as to leavethe piston Wings23, 24:, 25 fully alined until the conveyance has reached the point inits travel the speed constant; whilst at, a later stage furtherresistance would be provided to bring the conveyance to rest at the.lower terminal. of its journey. On the other hand when rock isbeing-raised from the mine, the relevant cam would be arranged to leavethe piston wings fully alined until the convey- 7 mice approaches thesurface, when it would cause said wings gradually to spread and soaiford the resistance suitable to bring the conveyance to rest at itsstopping point. In each case the fellow cam of the pair would be used onthe return journey.

We claim:

1. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rod and tail rod of equal diameterextending from the piston through the cylinder ends, said pistoncomprising relatively rotatable units providing a passage through thepiston the effective area of which is varied by relative rotation of thepiston units, and said tail rod being rotatable and connected to one ofsaid piston units to rotate the latter, and means for preventingrotation of another of said piston units.

2. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rod and tail rod of equal diameterextending from the. piston through the cylinder ends, said pistoncomprising relatively rotatable units providing a passage through thepiston the effective of the units, and said tail rod being rotatable andconnected to one of said piston units to rotate the latter, means forpreventing rotation of another of said piston units, afurther pistonunit being loose and rotatable with lost motion by the tail rod unit andhaving its angular movement limited by the nonrotatable unit. V i

3. A braking device comprising a cylinder adapted to contain liquid, a.piston reciprocable therein, a piston rod and tail'rod of equal diameterextending from the piston through the cylinder ends, saidpistoncomprising relatively rotatable units providing a passage through thepiston the effective area of which is varied by relative rotation of thepiston units, a rotatable and endwise fixed member'external' of thecylinder, and means for preventing rotation of one of said piston units,said tail rod being rotatableand connected to another of said pistonunits to rotate the latter and splined to the rotatable and endwisefixed member external of the cylinder. r

4. A braking device comprising a cylinder adapted to contain liquid, apiston reciproarea of which is varied by relative rotation I cabletherein, a piston rod and tail rod of equal diameter extending from thepiston through the cylinder ends, said piston comprising relativelyrotatable units providing a passage through the piston the effectivearea of which is varied by relative rotation of the pistonunits, arotatable and endwise fixed member external of the cylinder, means forpreventing rotation of one of'said piston units, said tail rod beingrotatable and connected to another of said piston units to rotate thelatter and splined to the rotatable and endwise fixed member external ofthe cylinder, and a further piston unit being loose and rotatable withlost motion by the tail rod unit.

5. A braking device comprising a cylinder containing liquid, a pistonreciprocable therein, a piston rod and tail rod of equal diameterextending from the piston through the cylinder ends, said pistoncomprising relatively rotatable units providing a passage through thepiston the effective area of which is varied by relative rotation of thepiston units, a rotatable and endwise fixed member external of thecylinder, means for preventing rotation of one of said piston units,said tail rod being rotatable and connected to another of said pistonunits to rotate the latter and splined to the rotatable and endwisefixed member external of the cylinder, a further piston unit being looseand rotatable with lost motion by the tail rod unit and having itsangular movement limited by the tail rod unit. 7

6. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rod and a tail rod of equaldiameter extending from the piston through the cylinder ends, saidpiston comprising at least three units each comprising sector-shapedwings comprising approximately not more than one-third of the possiblepiston area around the rods, the units being angularly adjustablerelatively to one another to provide a liquid passage through the pistonvariable from zero to at least approximately two-thirds of the possiblepiston area around the rods.

7. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rod and a tail rod of equaldiameter extending from the piston through the cylinder ends, saidpiston consisting of one piston unit comprising two end sets of at leastone sector-shaped wing, said wings being evenly spaced apart, andfurther piston units each with one set of at least two sector-shapedwings also evenly spaced apart, arranged with their wings between thetwo fixed sets, all the units being rotatable relatively to one another.

8. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rodand a'tail rod of equaldiameter extending from the piston through the cylinder ends, saidpiston con- V sisting of one piston unit comprising two end sets of atleast one sector-shaped wing, said wings being evenly spaced apart, andfurther piston units each with one set of at least two sector-shapedwings also evenly spaced apart,

arranged with their wings between the two fixed sets, means engaging oneof the piston units to prevent it from rotating and means fordifferentially rotating the other two piston units.

9. A braking device comprising a cylinder adapted to contain liquid, apiston reciprocable therein, a piston rod and a tail rod of equaldiameter extending from the piston through the cylinder ends, saidpiston consisting of one piston unit comprising two end sets of at leastone sector-shaped Wing, said wings being evenly spaced apart and furtherpiston units each with one set of at least two sector-shaped wings alsoevenly spaced apart, arranged with their wings between the two fixedsets, means engaging one of the piston units to prevent it fromrotating, means for positivelyrotating another of said piston units, athird piston unit being loosely rotatable, the second named piston unitbeing constructed to engage the third piston unit so as to rotate itwith lost motion and the first named piston unit beingconstructed toengage the third unit to limit its angular movement.

10. A braking device as claimed in claim 9 in which the second namedpiston unitis secured to the tail rod to rotate therewith, and arotatable and endwise fixed member external of the cylinder to which thetail rod is splined. v

In testimony whereof we afiix our signatures.

SYDNEY EDWARD THACKER EWING. ARTHUR LINDSEY EGAN

